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Implement per-CPU arena.

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The new feature, opt.percpu_arena, determines thread-arena association
dynamically based CPU id. Three modes are supported: "percpu", "phycpu"
and disabled.

"percpu" uses the current core id (with help from sched_getcpu())
directly as the arena index, while "phycpu" will assign threads on the
same physical CPU to the same arena. In other words, "percpu" means # of
arenas == # of CPUs, while "phycpu" has # of arenas == 1/2 * (# of
CPUs). Note that no runtime check on whether hyper threading is enabled
is added yet.

When enabled, threads will be migrated between arenas when a CPU change
is detected. In the current design, to reduce overhead from reading CPU
id, each arena tracks the thread accessed most recently. When a new
thread comes in, we will read CPU id and update arena if necessary.
This commit is contained in:
Qi Wang
2017-02-02 17:02:05 -08:00
committed by Qi Wang
parent 8721e19c04
commit ec532e2c5c
16 changed files with 415 additions and 119 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
test/unit/mallctl.c
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@@ -160,6 +160,7 @@ TEST_BEGIN(test_mallctl_opt) {
TEST_MALLCTL_OPT(bool, abort, always);
TEST_MALLCTL_OPT(const char *, dss, always);
TEST_MALLCTL_OPT(unsigned, narenas, always);
TEST_MALLCTL_OPT(const char *, percpu_arena, always);
TEST_MALLCTL_OPT(ssize_t, decay_time, always);
TEST_MALLCTL_OPT(bool, stats_print, always);
TEST_MALLCTL_OPT(const char *, junk, fill);
@@ -327,20 +328,38 @@ TEST_BEGIN(test_tcache) {
TEST_END
TEST_BEGIN(test_thread_arena) {
unsigned arena_old, arena_new, narenas;
size_t sz = sizeof(unsigned);
unsigned old_arena_ind, new_arena_ind, narenas;
const char *opt_percpu_arena;
size_t sz = sizeof(opt_percpu_arena);
assert_d_eq(mallctl("opt.percpu_arena", &opt_percpu_arena, &sz, NULL,
0), 0, "Unexpected mallctl() failure");
sz = sizeof(unsigned);
assert_d_eq(mallctl("arenas.narenas", (void *)&narenas, &sz, NULL, 0),
0, "Unexpected mallctl() failure");
assert_u_eq(narenas, opt_narenas, "Number of arenas incorrect");
arena_new = narenas - 1;
assert_d_eq(mallctl("thread.arena", (void *)&arena_old, &sz,
(void *)&arena_new, sizeof(unsigned)), 0,
"Unexpected mallctl() failure");
arena_new = 0;
assert_d_eq(mallctl("thread.arena", (void *)&arena_old, &sz,
(void *)&arena_new, sizeof(unsigned)), 0,
"Unexpected mallctl() failure");
if (strcmp(opt_percpu_arena, "disabled") == 0) {
new_arena_ind = narenas - 1;
assert_d_eq(mallctl("thread.arena", (void *)&old_arena_ind, &sz,
(void *)&new_arena_ind, sizeof(unsigned)), 0,
"Unexpected mallctl() failure");
new_arena_ind = 0;
assert_d_eq(mallctl("thread.arena", (void *)&old_arena_ind, &sz,
(void *)&new_arena_ind, sizeof(unsigned)), 0,
"Unexpected mallctl() failure");
} else {
assert_d_eq(mallctl("thread.arena", (void *)&old_arena_ind, &sz,
NULL, 0), 0, "Unexpected mallctl() failure");
new_arena_ind = percpu_arena_ind_limit() - 1;
if (old_arena_ind != new_arena_ind) {
assert_d_eq(mallctl("thread.arena",
(void *)&old_arena_ind, &sz, (void *)&new_arena_ind,
sizeof(unsigned)), EPERM, "thread.arena ctl "
"should not be allowed with percpu arena");
}
}
}
TEST_END